1. Field of the Invention
The present invention relates generally to compositions and methods for regulating the growth of plants, and more particularly to compositions and methods for producing uniformly stocky plants.
2. Background of the Invention
Transplants have long been used in the vegetable industry to help schedule production, extend the producing season, and gain the advantage of higher prices available to sellers at earlier markets. Further, with some crops it is necessary to use transplants because seed germination cannot effectively be accomplished under cold or otherwise harsh field conditions. Accordingly, the transplant industry is rapidly expanding to meet increased market demand driven by new production technology, high seed costs and the need to reduce production risk.
Vegetable transplants often require treatment to slow their growth. Weather conditions or other factors may dictate a schedule change, or growth reduction may be necessary when transplants are produced under cloudy or high temperature conditions which cause undesirably spindly plants. Short and stocky transplants are easier to ship and handle during the transplanting operation and they better withstand transplant stress. Likewise, as automatic transplanters are developed, the demand for very uniform plants will be greater to allow the automatic planters to operate most efficiently.
It is known that plant growth is regulated by chemical substances, particularly plant hormones, produced within the plant. These plant hormones are organic compounds produced by the plant and active in small amounts which are transported through the plant body influencing growth or other physiological processes. Unlike enzymes, hormones are consumed during metabolic processes and must be renewed if their effects are to continue.
Traditionally, commercial plant regulators have been formulations or synthetic analogs of the following major plant hormone classes: Auxins, Cytokins, Ethylene generators, and Gibbrellins. Occasionally, other hormones have been used.
Plant growth is also regulated by environmental factors, such as changes in water potential and temperature. For example, when a plant is exposed to water stress (drought, cold and salt stress), water potential decreases as does the cellular growth of the plant. Decreasing external water potential by -0.1 Mpa (sometimes less) results in a perceptible decrease in cellular growth.
Due to recent restrictions on the use of chemical plant growth regulators, the development of alternative methods of practical growth control and conditioning of transplants has been increasingly studied. In this regard, growers are using water/fertilizer restriction, temperature regulation, and mechanical brushing to attempt to achieve desired growth regulation results. None of these prior art methods, however, has provided the desired results in an economically advantageous manner.
A need therefore exists for plant growth regulations which are non-toxic to the plants, environmentally acceptable and relatively inexpensive. The present invention addresses that need by providing compositions and methods which reduce plant growth and condition the plants for hardiness against environmental and handling stresses.